The present technology relates to an electrolytic solution, to a secondary battery that uses the electrolytic solution, and to a battery pack, an electric vehicle, an electric power storage system, an electric power tool, and an electronic apparatus that use the secondary battery.
In recent years, various electronic apparatuses such as mobile phones and personal digital assistants (PDAs) have been widely used, and it has been demanded to further reduce the size and the weight of the electronic apparatuses and to achieve their long life. Accordingly, a battery, in particular, a small and light-weight secondary battery capable of providing high energy density has been developed as an electric power source. In these days, it has been considered to apply such a secondary battery to various other applications that may include, for example, battery packs attachably and detachably mounted on the electronic apparatuses or the like, electric vehicles such as electric automobiles, electric power storage systems such as home electric power servers, and electric power tools such as electric drills.
As secondary batteries, secondary batteries that obtain a capacity by utilizing various charge and discharge principles have been proposed. In particular, secondary batteries that utilize insertion and extraction of electrode reactants are considered promising, since such secondary batteries provide higher energy density than batteries such as lead batteries and nickel-cadmium batteries.
A secondary battery includes a cathode, an anode, and an electrolytic solution. The electrolytic solution includes a solvent and an electrolyte salt. The electrolytic solution that functions as an intermediate in charge and discharge reactions largely affects performance of the secondary battery. Hence, the composition of the electrolytic solution has been variously studied. Specifically, a cyclic ester carbonate that has one or more carbon-carbon unsaturated bonds is used as an additive for an electrolytic solution so as to suppress, for example, battery deterioration in high-voltage charge, risk of explosion resulting from pressure increase inside the battery, etc. (for example, see Japanese Unexamined Patent Application Publication Nos. 2006-114388, 2001-135351, H11-191319, 2000-058122, and 2008-010414, and Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2004-523073). Such a cyclic ester carbonate is not limitedly used in batteries (liquid batteries) that use an electrolytic solution, but also used in batteries (solid batteries) that do not use an electrolytic solution (for example, see Japanese Unexamined Patent Application Publication No. 2003-017121).